Apatosaurus ("deceptive lizard") is a dinosaur that lived 155-145 million years ago during the Late Jurassic period.
It was first seen as a herd eating water grass. When the Tyrannosaurus lunged for the herbivores, Apatosaurus ran and watched its showdown with Stegosaurus. It is then seen marching with the other dinosaurs during the drought. They are then trapped in the muddy pit with other Stegosaurs, and they die of heat exhaustion and are attacked by desperately hungry Ceratosaurs.
An Apatosaurus herd makes an appearance in the episode "Tarzan and the Hidden World".
Arlo and his family are Apatosaurus which are the central dinosaurs in the Pixar film.
- Apatosaurus shares a lot of similarities with Diplodocus: they both are sauropods, both eat plants, both are diplodocoids, and both lived in the Jurassic Period of North America.
- Brontosaurus and Apatosaurus were once thought to be one and the same. However, examinations of the two in 2015 show that Brontosaurus is, in fact, a separate animal from Apatosaurus, but at the same time is its closest relative in a family of diplodocids called the Apatosaurinae.
- Apatosaurus was able to walk on two legs as a baby (based on footprints) and walked on all fours as it grew into an adult.
- Apatosaurus and other diplodocids were able to move their tails fast enough to break the sound barrier; this is believed to have been a useful defense against predators.